1. Field of the Invention
The invention relates to the field of vertically stacked field programmable non-volatile memory and method of fabrication.
2. Prior Art
Recently there has been an interest in fabricating memories having memory cells disposed at numerous levels above a substrate. Each level includes a plurality of spaced-apart first lines extending in one direction which are vertically separated from a plurality of parallel spaced-apart second lines in a second direction, for example, extending perpendicular to the first line. Cells are disposed between the first lines and second lines at the intersections of these lines. These memories are described in U.S. Pat. Nos. 5,835,396 and 6,034,882.
As will be seen, the present invention departs from the structures shown in these patents and uses “rail-stacks” as will be described later. The invented memory employs antifuses where a diode is formed upon programming a particular bit. In this connection see, “A Novel High-Density Low-Cost Diode Programmable Read Only Memory,” by de Graaf, Woerlee, Hart, Lifka, de Vreede, Janssen, Sluijs and Paulzen, IEDM-96, beginning at page 189 and U.S. Pat. Nos. 4,876,220; 4,881,114 and 4,543,594.